1. Field of the Invention
The present invention is related to fixtures used for installing or removing coil springs, and particularly to a fixture used for installing or uninstalling a coil spring into or from an electrical connector. The present invention is also related to a method of using the fixture to install and remove the coil spring.
2. Description of the Prior Art
Electrical connectors are widely used for electrically connecting electronic packages such as integrated circuits (ICs) with substrate circuits such as burn-in boards. Referring to FIGS. 6 and 7, a typical electrical connector 3′ comprises an insulative housing 30′ to be mounted on a burn-in board (not shown), a number of electrical contacts (not shown) received in the housing 30′ and electrically connecting with the burn-in board, a pair of actuation members 34′ assembled on two opposite sides of the housing 30′, and a lid 32′ assembled on the actuation members 34′ and capable of moving relative to the housing 30′. The housing 30′ defines four first step holes 300′ in four corners thereof. The lid 32′ defines four second step holes 320′ in four corners thereof, the second step holes 320′ corresponding to the first step holes 300′. Four coil springs 36′ are assembled between the housing 30′ and lid 32′, with ends of the springs 36′ engaging in the first and second step holes 300′, 320′, respectively. When the lid 32′ is pressed down to drive the actuation members 34′, an IC (not shown) can be attached on the connector 3′ with Low Insertion Force. When the lid 32′ is released, the springs 36′ rebound to drive the lid 32′ up automatically and the IC can be securely received in the connector 3′.
During assembly of the connector 3′, the actuation members 34′ are assembled on the housing 30′. The lid 32′ is assembled on the actuation members 34′. A vertical height between a bottom surface of the lid and a top surface of the housing is defined, signed with B in FIG. 7A. The springs 36′ are assembled between the lid 32′ and the housing 30′. Because a vertical height between the housing 30′ and the lid 32′ is smaller than a length of each of the springs, it is difficult to install or uninstall the springs 36′ into or from the connector 3′ by hand. Therefore, a fixture is generally needed.
A typical fixture 1′ comprises a generally cylindrical handle 12′, a J-shaped pin 14′ coaxially extending from an end of the handle 12′, and a lever 16′ assembled perpendicularly on an opposite end of the handle 12′ via a screw 18′. The pin 14′ forms a hook 140′ at a free end thereof, the hook 140′ having a length marked with A in FIG. 7A. The lever 16′ forms a wedge 160′ at a free end thereof, the wedge 160′ extending perpendicularly from the lever 16′.
A method of installing one of the springs 36′ into the connector 3′ by the fixture 1′ generally comprises the following steps:    A. Inserting the hook 140′ of the fixture 1′ into a bottom end of the spring 36′;    B. Putting an opposite top end of the spring 36′ into one of the second step holes 320′ of the lid 32′;    C. Lifting up the fixture 1′ to compress the spring 36′;    D. Moving the bottom end of the spring 36′ near the first step hole 300′ of the housing 30′;    E. Withdrawing the hook 140′ from the spring 36′ to make the spring 36′ abut against a surface of the housing 30′ near the first step hole 300′; and    F. Pushing the bottom end of the spring 36′ into the first step hole 300′ thereby securely installing the spring 36′ into the connector 3′.
In above-mentioned operation, it is difficult to withdraw the hook 140′ from the spring 36′ in step D because the hook 140′ is inserted into the bottom end of the spring 36′. When the fixture 1′ is forcedly withdrawn, the spring 36′ is liable to be detached away from the connector 3′ with the fixture 1′ such that the operation fails. Additionally, the more longer the spring is, the more difficultly the top end of the spring 36′ is put into the second step hole 320′ of the lid 32′ in step B, because of the hook 140′ inserted into the bottom end of the spring 36′.
On the other hand, increasing the height A of the hook 140′ is benefit to securely attach the spring 36′ to the hook 140′. When the height A of the hook 140′ is higher than the vertical height B between the lid 32′ and the housing 30′, the fixture 1′ may be unlikely inserted into a space between the lid 32′ and the housing 30′ thus installing the spring 36′ is not completed. When the height A of the hook 140′ is short, the spring 36′ is liable to escape from the hook 140′ thus the assembly operation can not go on.
A method of uninstalling one of the springs 36′ from the connector 3′ generally comprises the following steps:    A. Inserting the wedge 160′ into a space between two adjacent coils of the spring 36′;    B. Lifting up the fixture 1′ to compress the spring 36′ until the bottom end of the spring 36′ is exposed out of the first step hole 300′ of the housing 30′; and    C. Withdrawing the fixture 1′ from the connector 3′ thereby uninstalling the spring 36′ from the connector 3′.
However, the spring 36′ is apt to escape from the wedge 160′ of the fixture 1′ thus the operation can be blocked.
In view of the above, a new fixture that overcomes the above-mentioned disadvantages is desired.